Pulm Physiology 3

Question 1

what is daltons law of partial pressure

Answer 1

-the sum of all partial pressures equals total pressure

Question 2

What is henrys law?

Answer 2

-gas will dissolve in a liquid in proportion to its partial pressure

Question 3

What happens when the partial pressure of CO2 is higher in the pulmonary capillaries than in the lungs?

Answer 3

-the CO2 diffuses from the pulmonary capillaries to the lungs.

Question 4

Do alveoli contain more CO2 and water vapor than atmospheric air?

Answer 4

-yes, d/t gas exchange at the lungs, humidification of air, and mixing of alveolar gas that occurs with each breath.

Question 5

amount of gas reaching the alveoli = ?

amount of blood flow reaching the alveoli = ?

Answer 5

ventilation

perfusion

• ventilation and perfusion must be matched for efficient gas exchange.

Question 6

Arterioles constrict when alveolar PO2 is _____. AKA

Why do they constrict?

Answer 6

low. shunting

they constrict to redirect blood to areas where PO2 is higher. When alveolar PO2 is high the arterioles dilate to increase blood flow and promote O2 transport.

Question 7

Bronchioles dilate when alveolar PCO2 is ____. Why?

Answer 7

high, to allow CO2 to be eliminated.

when alveolar PCO2 is low the bronchioles constrict.

Question 8

how is O2 transported?

Answer 8

• 1.5% dissolved in plasma

- 98.5% loosely bound to each Fe or Hb in RBCs

Question 9

As O2 binds, Hb affinity for O2 ______.

As O2 is released, Hb affinity for O2 _____.

Answer 9

• increases.

- decreases.

Question 10

Rate of loading and unloading of O2 is regulated by?

Answer 10

• PO2
• temp
• pH
• PCO2
• Concentration of BPG (rises when O2 uptake in the lungs is compromised)

Question 11

_____ blood has the highest % of saturated hgb?

Answer 11

arterial blood, PO2 = 100mmHg

Hgb 98% saturation

Question 12

Increases in ___, ___, ___, ___ will modify the structure of hgb and decrease its affinity for O2.

Answer 12

temp, H+ (decrease pH), PCO2, and BPG

these enhance O2 unloading and shift the O2-hgb dissociation curve to the RIGHT. Decreases in these will shift the curve to the LEFT.

Question 13

When is BPG released? What does this do?

Answer 13

• released when O2 levels are chronically low
• decreases affinity of O2 for Hb allowing the O2 to be released (unloaded) so that it can go to the tissue where its needed.

Question 14

How is CO2 transported?

Answer 14

• dissolved in plasma (7-10%)
• bound to hgb (20%)
• bicarbonate ions HCO3- (70%)

Question 15

describe the chemical rxn that takes place allowing CO2 to be transported from the TISSUES back to blood.

Answer 15

typically in the red blood cell…
CO2+ H2O+ (carbonic anyhdrase) = H2CO3 (carbonic acid) = HCO3- + H
**HCO3- quickly diffuses from RBC into the plasma, HCO3- is exchanged for Cl- in the RBC.

Question 16

Describe the rxn that takes place in the pulmonary capillaries to expel CO2.

Answer 16

in the pulmonary capillaries HCO3- moves back into RBC and binds with H+ to form H2CO3 (Carbonic acid). H2CO3 is split by carbonic anhydrase into CO2 and H20. CO2 is able to diffuse into alveoli.

Question 17

What is the Haldane Effect

Answer 17

the amount of CO2 transported is affected by PO2.

*The lower the PO2 and Hgb saturation with O2 the more CO2 can be carried in the blood.

Question 18

How does CO2 affect blood pH?

Answer 18

increased levels of CO2 causes pH to drop.

Question 19

How do H+ ions and bicarbonate work to regulate blood pH?

Answer 19

• if H+ in the blood rises, excess H+ is removed by combining with HCO3- and blood pH lowers..
• if H+ concentration in blood is too low then carbonic acid dissociates and becomes HCO3- and pH increases.

Question 20

What are the 4 factors that influence respiration?

Answer 20

Neural Mechanisms:

• Ventral Resp Group & Dorsal Respiratory Group from the medulla
• Pontine Res Groups

Chemical Factors:

• arterial pH
• PO2
• PCO2

Lung reflexes

emotions

Question 21

How are depth and rate determined in respiration?

Answer 21

• depth: how actively the respiratory center stimulates the respiratory muscle
• rate: how long the inspiratory center is active.

Question 22

Hyperventillation causes ____ levels to ____.

Answer 22

CO2 levels to decline leading to a period of apnea (so that PCO2 is able to accumulate to normal levels again)

Question 23

Where are the peripheral chemoreceptors that sense O2?

How low must arterial PO2 become in order to stimulate increased ventilation by these receptors?

Answer 23

• aortic and carotid bodies

- the arterial PO2 must drop to 60mmHg (normal PO2 functions at 70mmHg)

Question 24

Decreased pH may reflect…?

Answer 24

• CO2 retention
• accumulation of lactic acid
• excess ketone bodies in patients with DM

Question 25

What is the most powerful respiratory stimulant?

Answer 25

rising CO2 levels

Question 26

Inflation Reflex:

-Hering- Breuer Reflex, what is this?

Answer 26

-stretch receptors in the pleurae and airways are stimulated by lung inflation; inhibitory signals to the medullary respiratory centers end inhalation and allow expiration to occur.

Question 27

Do PCO2, PO2, and pH remain constant during exercise?

Answer 27

why yes they do.

Question 28

Acclimization to High Altitude

• what happens to chemoreceptors when PO2 declines?
• what hematopoietic adjustments are made?

Answer 28

• they become more responsive to PCO2

- declind in O2 stimulates EPO production thereby increasing the number of RBC made.